[参考译文] TMS320F28035-DAC：EP 和 DAC 之间的 SPI 通信未正常工作

我更改了 SPICHAR、 CLKPOLARITY、 CLK_PHASE、如下所示、并获得了屏幕截图所示的波形。 仍然 CS 不会变为低电平

SPICCR： 1111

SPICHAR：0-3：16位字(F)

SPILBK：4：禁用环回功能

CLKPOLARITY：6：=数据在上升沿输出、在下降沿输入。 当未发送 SPI 数据时、SPICLK 处于低电平。

数据输入和输出边沿取决于时钟相位位位的值

SPICTL：0110

SPIINTENA： 禁用中断。 (0)

Talk :启用传输(1`)

master_slave： SPI 配置为主器件。(1)

CLK_PHASE :=正常的 SPI 时钟方案,取决于时钟极性位(SPICCR.6)(0)

void spi_configureSPIAModule(void)
{
    EALLOW;

    GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 1; // SPISIMOA (MOSI)
    GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 1; // SPISOMIA (MISO)
    GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 1; // SPICLKA (CLK)
    GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 1; // SPISTEA (CS)

    GpioCtrlRegs.GPAPUD.bit.GPIO16 = 0;
    GpioCtrlRegs.GPAPUD.bit.GPIO17 = 0;
    GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0;
    GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0;

    // SPI configuration
    SpiaRegs.SPICCR.bit.SPISWRESET = 0;   // Hold SPI in reset
    SpiaRegs.SPICCR.all = 0x000F;         // 16-bit, CPOL = 0, reset held
    SpiaRegs.SPICTL.all = 0x0006;         // Master, CPHA = 1
    SpiaRegs.SPIBRR = 0x007F;             // SPI baud rate ~468.75kHz @ 60MHz
    SpiaRegs.SPICCR.bit.SPISWRESET = 1;   // Release SPI

    SpiaRegs.SPIPRI.bit.FREE = 1;         // Free run mode

    EDIS;
}

void spi_writeToDAC(Uint8 regAddr, Uint16 value)
{
    Uint8 cmdByte = 0;
    Uint16 word1 = 0;
    Uint16 word2 = 0;

    // Bit 23 = 0 (Write), Bits 22–20 = 000 (reserved), Bits 19–16 = register address
    cmdByte = (regAddr & 0x0F);

    // Build 24-bit frame as two 16-bit writes (MSB first)
    word1 = (cmdByte << 8) | ((value >> 8) & 0xFF);   // First 16 bits: [Command][Data[15:8]]
    word2 = (value & 0xFF) << 8;                      // Last 8 bits: [Data[7:0]] in upper byte

    GpioDataRegs.GPACLEAR.bit.GPIO19 = 1; // CS low

    // Send word1
    SpiaRegs.SPITXBUF = word1;
    while (SpiaRegs.SPISTS.bit.INT_FLAG == 0);
    SpiaRegs.SPISTS.all = 0x0000;

    // Send word2
    SpiaRegs.SPITXBUF = word2;
    while (SpiaRegs.SPISTS.bit.INT_FLAG == 0);
    SpiaRegs.SPISTS.all = 0x0000;

    GpioDataRegs.GPASET.bit.GPIO19 = 1; //CS high
}